ValueConverter to convert an IEnumerable of anything into a string with custom separator

EnumerableToTextConverter.cs

using System;
using System.Collections;
using System.Linq;
using System.Windows.Data;

namespace LedgerscopeApplication.ValueConverters
{
    public class EnumerableToTextConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            if (parameter == null)
                parameter = Environment.NewLine;
            var val = value as IEnumerable;
            if (val != null)
            {
                var retVal = string.Join(parameter.ToString(), val.OfType<object>().Select(a => a.ToString()));
                return retVal;
            }
            else
            {
                return string.Empty;
            }
        }

        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }
}